Wood preservatives

ABSTRACT

A wood preservative composition and method for preserving wood by contacting wood with said composition comprising a polyurethane polymer, non-aqueous solvents, and a wood preservative active.

The present invention relates to a wood preservative composition andmethod for preserving wood to impart protection from wood-decayingorganisms.

There are many methods and compositions for preserving wood prior to thetime the wood is put in use. Also, preservatives for treating wood inplace are available on the market including both oil-based andwater-based products. The oil-based products generally consist ofpetroleum oils with pentachlorophenol or creosote. U.S. Pat. No.7,959,723 describes one such composition employing oil-solublepreservatives for wood. From the standpoint of toxicity andenvironmental pollution, these active ingredients are less thandesirable.

The problem addressed by this invention is the need for a moreenvironmentally friendly wood treatment composition which is capable ofefficaciously imparting active ingredients.

The present invention is directed to a method for preserving woodcomprising contacting wood with a wood preservation compositioncomprising a) a polyurethane polymer synthesized from a polyolcomprising >95% p-propylene oxide; an isocyanate, and a capping agent;b) an organic solvent; and c) at least one wood preservative activeselected from among halogenated isothiazolone biocides, halogenatedcarbamate fungicides and azole fungicides; wherein the capping agent isselected from the group consisting of a mono alcohol, a secondary amine,a primary amine with alkyl chain greater than C15 and mixtures thereof;and further wherein the molecular weight of the polyol is greater thanor equal to 2700.

The present invention is further directed to a wood preservationcomposition comprising a) a polyurethane polymer synthesized from apolyol comprising >95% p-propylene oxide; an isocyanate, and a cappingagent; b) an organic solvent; and c) at least one wood preservativeactive selected from among halogenated isothiazolone biocides,halogenated carbamate fungicides and azole fungicides; wherein thecapping agent is selected from the group consisting of a mono alcohol, asecondary amine, a primary amine with alkyl chain greater than C15 andmixtures thereof; and further wherein the molecular weight of the polyolis greater than or equal to 2700.

All percentages and part per million (ppm) values are on the basis oftotal weight of the composition, unless otherwise indicated. The terms“a” or “an” refer both to the singular case and the case where more thanone exists. All range endpoints are inclusive and combinable. Ascontained herein all molecular weights are number average molecularweight and are determined by Gel Permeation Chromatography (GPC). It isenvisioned that one skilled in the art could select and/or combinemultiple suitable and/or preferred embodiments in the present invention.

The wood preservative compositions of the present invention comprisepolyurethane polymers that are synthesized from bis hydroxy terminatedpolypropylene oxide macromere (polyol), an isocyanate, and anappropriate capping agent. Polyurethane polymers, as used herein, maycontain other functional groups derived from reaction of isocyanateswith other monomers, e.g., amide groups derived from carboxylic acids,and ureas derived from amines, e.g. ethylene diamine (EDA) or otherpolymers, such as polyesters, e.g., polyesters derived from adipic acidand 1,6-hexanediol, 1,4-butanediol and/or neopentyl glycol, orpolycarbonates, e.g. polycarbonates derived from poly 1,6-hexanediolcarbonate. Suitable isocyanates include, e.g., methylenebis(4-cyclohexylisocyanate) (MCI), methylene bis(4-phenylisocyanate)(MDI), polymethylenepolyphenol isocyanate (pMDI), hexamethylenediisocyanate (HDI), isophorone diisocyanate (IPDI) and toluenediisocyanate (TDI) and combinations thereof. Preferably, the isocyanatesof the present invention are diisocyanates. Examples of suitablediisocyanates include IPDI, pMDI, MDI and combinations thereof. Morepreferably, the diisocyanate is IPDI. The polyol used to make thepolyurethane in the present invention is >95% p-propylene oxide having amolecular weight greater than or equal to 2700. Suitably the isocyanateto polyol molar ratio of the polyurethane polymers is from less than 4to greater than or equal to 1.05, alternatively from less than or equalto 2 to greater than or equal to 1.05

Polyurethane polymers of the present invention are capped. According tothe present invention, the capping agent is an amine or alcohol. Thepolyurethane is capped with a monoamine or monoalcohol, for examplebutyl amine, octanol, octyl amine or combinations thereof. Specifically,the capping agent is at least one of a mono primary alkyl amine, monosecondary alkyl amine or mono alcohol. In accordance with the presentinvention, all primary alcohol, all secondary amine, and >C15 alkylchain primary amine capping agents are suitable and mixtures thereof.The polyurethane polymer is synthesized in a non-aqueous solvent or amixture of non-aqueous solvents. Preferably, the amount of solvent isfrom 60% to 90%, more preferably from 70% to 90%, and most preferablyfrom 75% to 90%. Suitable solvents include ester and ether solventshaving a boiling point of at least 150° C., and preferably a flash pointof at least 60° C. Examples of such solvents include, alkanes, branchedalkanes, aromatics, e.g., Mineral spirits, toluene, benzyl alcohol,xylenes, and alkyl benzenes. A suitable mixture of non-aqueous solventsuseful in the present invention is Aromatic 200 (CAS No. 64742-94-5).

The wood treatment composition of the present invention, in addition topolyurethane polymer, further comprises a wood preservative active. Thewood preservative active may be selected from the class of halogenatedisothiazolinone biocides, halogenated carbamate fungicides, metal saltsof naphthenic acids, and azole fungicides. When the wood preservativeactive is a halogenated isothiazolinone biocide, it preferably comprisesa 3-isothiazolone having a C4-C12 N-alkyl substituent, more preferably achlorinated 3-isothiazolone, and most preferably4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (“DCOIT”). Mixtures of woodpreservatives actives may be used. When the polyurethane polymer iscombined with DCOIT a suitable composition includes 23% polyurethanepolymer solids, 23% DCOIT, and 54% Aromatic 200.

The composition used to treat wood preferably contains from 100 ppm to40,000 ppm wood preservative, more preferably from 200 ppm to 30,000ppm, and most preferably from 300 ppm to 25,000 ppm. Preferably, thepolymer solids content of the composition is from 10% to 40%, morepreferably from 10% to 30%, and most preferably from 15% to 30%.Preferably, the polymer solids to biocide ratio is from 2:1 to 1:2, morepreferably from 2:1 to 1:1.

Another critical element of the wood preservation composition is anorganic solvent. The polyurethane polymer is diluted with organicsolvent. Suitably, the organic solvent is diesel, however other organicsolvents known to those of skill in the art may be used. In someembodiments the organic solvent is not the same compound as thenon-aqueous solvent of the present invention. As used herein, diesel isdefined as the fractional distillation of crude oil between 200° C.(392° F.) and 350° C. (662° F.) at atmospheric pressure, resulting in amixture of carbon chains that typically contain between 8 and 21 carbonatoms per molecule or biodiesel that is obtained from vegetable oil oranimal fats (biolipids) which have been transesterified with methanol(fatty-acid methyl ester (FAME)) and mixtures thereof.

The compositions used in the present invention may optionally containadditional components including but not limited to stabilizers, dyes,water repellents, other wood biocides, fungicides and insecticides,antioxidants, metal chelators, radical scavengers, etc. Stabilizersinclude, e.g., organic and inorganic UV stabilizers, such as, copperoxide or other copper salts or complexes that resist leaching; zincoxide; iron salts, iron oxide, iron complexes, transparent iron oxideand nanoparticle iron oxide; titanium dioxide; benzophenone andsubstituted benzophenones; cinnamic acid and its esters and amides;substituted triazines, such as triphenyl triazine and substituted phenyltriazine UV absorbers, benzotriazole and substituted benzotriazole UVabsorbers; hindered amine light stabilizers, used individually or incombination. Water repellents include, e.g., various wax-type waterrepellents, e.g., paraffin, carnauba, and polyethylene waxes; andsilicones. Other wood biocides, fungicides, such as copper metal,bethoxazin and cyproconazole, chlorothalonil, tebuconazole,propiconazole, pentachlorophenol, creosote, copper napthenate, dialkyldimethyl quaternary ammonium carbonate/bicarbonate, and insecticidesinclude, e.g., those listed in U.S. Pat. No. 6,610,282, e.g.,imidacloprid, thiacloprid, permethrin, and etofenprox. Antioxidantsinclude any commercially available antioxidant compounds, e.g.,phosphite antioxidants such as IRGAFOS; lactone antioxidants; phenolicantioxidants such as BHT; ascorbic acid; and IRGANOX and the like. Metalchelators include, e.g., EDTA, NTA, 1,10-phenanthroline, ACUMER 3100,DEQUEST, TAMOL 731, tripolyphosphate and other inorganic and organiccompounds and polymers useful in chelating or dispersing metal salts.Radical scavengers include, e.g., TEMPO.

Preservation of wood is performed by contacting the wood with the woodpreservation composition described herein, preferably under conditionsthat comply with American Wood Protection Standards T1-16 and meetconditions for use specified in U1-16. In order to provide long termprotection, the preservative needs to “fix” in the wood and not depletetoo rapidly by volatilization or by leaching when the wood gets wet. Itmight be expected that enhanced penetration or enhanced movement of thepreservative deep into the wood during treatment might also lead toreduced fixation of the organic wood preservative active.

EXAMPLES Synthesis of Polyurethane Polymers:

The following polyurethanes were synthesized from a bis hydroxyterminated polypropylene oxide (polyol) and a diisocyanate (IPDI orMDI). 150 mL of anhydrous polypropylene oxide in aromatic 200 (solvent,10-30 wt % solution), diisocyanate (2 molar equivalents of isocyanatesto hydroxyl groups), was charged with 0.003% of a tin catalyst(dibutyltin dilaurate) to the reactor. Polyols of three varyingmolecular weights were tested: 4000 MW, 2700 MW, and 2000 MW. Thereactor was heated to 90° C. with overhead stirring. The reactionmixture was held at 90° C. for 1 h.

The residual isocyanate, in the polyurethane capped examples, ismeasured using Surface SWYPE™ test strips. The reaction product wascooled to room temperature and the capping reagent, mono amine (1equivalent amine to unreacted isocyanate) was added to cap the remainingisocyanate groups in the reaction mixture. Alternatively, when monoalcohol (1 equivalent hydroxyl to unreacted isocyanate) was used as thecapping reagent it was added at 90° C. and reacted for an additional 1 hat 90° C. The reaction is continued at 90° C. until no free isocyanatewas observed when tested with SWYPE™ test strips. The polymer solids ofthe PU solution was estimated from the conversion and the amount ofreactants used for the reaction. The polymer solids are calculated asthe sum of the reactive components in the synthesis of the polymer.

Procedure to Determine Diesel Compatibility:

In a clear, 1 oz vial, 0.1 gram of the polymer (on a 100% polymer solidsbasis) is diluted with 9.9 grams of diesel fuel (weight/weight) to a 1%solution of the polymer. The sample is maintained at room temperaturefor 48 hours. After 48 hours, the solution is checked forincompatibility, defined as phase separation, precipitation of thepolymer as solids, and/or turbidity.

Calculations of Hansen Solubility Parameters:

Hansen solubility parameters (HSP) for the various polyurethane end capsegments were computed using HSPiP software (Purchased fromhttps://www.hansen-solubility.com/). Predicted HSPs (using the Y-MBmethod), namely, the HSP for the dispersion (D), polar (P), and hydrogenbonding (H) contributions (all SP in MPa1/2), the total SP (calculatedusing the predicted HSP), and “End cap distance from diesel” werecomputed. According to the HSP theory, the distance between twomaterials is a measure of the solubility. The smaller the distance themore soluble the fluids are within one another. HSP data for a “diesel”was obtained from the literature (Batista et al. J. Am. Oil Chem. Soc.V92, 95, 2015).

δ_(T)=√{square root over (δ_(D) ²+δ_(P) ²+δ_(H) ²)}

R _(a)=√{square root over(4(δ_(D1)δ_(D2))²+4(δ_(P1)=δ_(P2))²+4(δ_(H1)−δ_(H2))²)}

δ_(D1)=Dispersive solubility parameter for Diesel=14.51δ_(D2)=Dispersive solubility parameter for a given end group (δ_(D))δ_(P1)=Polar solubility parameter for Diesel=3.18δ_(P2)=Polar solubility parameter for a given end group (δ_(P))δ_(H1)=H-bonding solubility parameter for Diesel=5.97δ_(H2)=H-bonding solubility parameter for a given end group (δ_(H))

TABLE 1 Diesel Compatibility of PU Polymers with 100% p-iPO and IPDIwith various cap segments (MW = 2700 to 4000) Diesel compatibilityCalculated Hansen Solubility (1 wt. %) Parameters (MPa^(1/2)) for EndPolyol Polyol Cap Segment and “End Cap” MW = 4000 MW = 2700 End Cappingdistance from “Diesel” (Ra) EX-1-22; EX-1-22; Example # Reagent δ_(T)δ_(D) δ_(P) δ_(H) Ra Comp 1-9 Comp 1-9 EX-1 Methanol 28.4 19.1 16 13.617.5 YES YES EX-2 1-Propanol 23.4 17.8 11.5 10 11.3 YES YES EX-32-Propanol 22.7 17.5 11.4 8.9 10.6 YES YES EX-4 1-Butanol 22.7 17.5 10.410 10.2 YES YES EX-5 2-Butanol 21.8 17.3 9.8 8.9 9.1 YES YES EX-6Sec-Butanol 21.7 17.2 10.1 8.5 9.1 YES YES EX-7 1-Pentanol 21.9 17.4 9.59.2 9.2 YES YES EX-8 1-Hexanol 21.1 17.2 8.9 8.4 8.2 YES YES EX-91-octanol 19.8 16.9 7.6 6.9 6.6 YES YES EX-10 Docosanol 17.1 16.2 4.33.4 4.4 YES YES EX-11 Propylene glycol 20.9 17 9.2 8 8.1 YES YES butylether EX-12 Dimethylamine 26.1 18.3 14.3 11.9 14.7 YES YES EX-13Diethylamine 23.1 17.3 12.2 9.3 11.1 YES YES EX-14 Di-n-butylamine 20.816.9 9.3 7.7 8 YES YES EX-15 Di-isobutylamine 19.7 16.5 8.8 6.1 6.9 YESYES EX-16 Dihexylamine 19.7 16.7 8.1 6.6 6.6 YES YES EX-17 Diheptylamine19.3 16.6 7.8 6.1 6.2 YES YES EX-18 Dioctylamine 18.6 16.5 6.8 5.4 5.4YES YES EX-19 Didecylamine 18.3 16.4 6.3 5 5 YES YES Comp.1 Benzylamine26 20.2 12.4 10.7 15.4 NO NO Comp.2 1-butylamine 25.6 18.1 13.2 12.413.9 NO NO Comp.3 1-pentylamine 24.5 17.9 12.2 11.5 12.6 NO NO Comp.41-hexylamine 22.7 17.5 10.9 9.6 10.4 NO NO Comp.5 1-octylamine 21.9 17.49.9 8.8 9.3 NO NO Comp.6 2-ethylhexylamine 21.7 17.3 9.7 8.8 9 NO NOComp.7 1-undecylamine 20.5 17.1 8.7 7.3 7.7 NO NO Comp.8 1-dodecylamine20 17 8.1 6.8 7 NO NO Comp. 9 1-Pentadecylamine 19.3 16.8 7.4 5.9 6.2 NONO Ex-20 1-Hexadecylamine 18.9 16.7 6.9 5.5 5.8 YES YES Ex-211-Heptadecylamine 18.8 16.7 6.7 5.4 5.6 YES YES Ex-22 1-Octadecylamine18.6 16.6 6.5 5.2 5.4 YES YES

In accordance with the present invention, all mono alcohol, allsecondary amine, and primary amine with alkyl chains greater than C15capping agents were compatible.

TABLE 2 Diesel Compatibility of PU Polymers with 100% p-iPO and IPDIwith various cap segments (MW = 2700 to 4000 Vs MW = 2000) Dieselcompatibility (1 wt. %) Calculated Hansen Solubility Polyol PolyolParameters (MPa^(1/2)) for End MW = 4000 MW = 2700 Cap Segment and “EndCap” EX. 1-6; EX. 1-6; Polyol End Capping distance from “Diesel” (Ra)EX. 12-17; EX. 12-17; MW = 2000 Polymer # Reagent δ_(T) δ_(D) δ_(P)δ_(H) Ra EX. 20-22 EX. 20-22 Comp. 10-24 EX-1; Methanol 28.4 19.1 16.013.6 17.5 YES YES NO Comp 10 EX-2; 1-Propanol 23.4 17.8 11.5 10.0 11.3YES YES NO Comp.11 EX-3; 2-Propanol 22.7 17.5 11.4 8.9 10.6 YES YES NOComp. 12 EX-4; 1-Butanol 22.7 17.5 10.4 10.0 10.2 YES YES NO Comp. 13EX-5; 2-Butanol 21.8 17.3 9.8 8.9 9.1 YES YES NO Comp 14 EX-6;Sec-Butanol 21.7 17.2 10.1 8.5 9.1 YES YES NO Comp 15 EX-12Dimethylamine 26.1 18.3 14.3 11.9 14.7 YES YES NO Comp 16 EX-13;Diethylamine 23.1 17.3 12.2 9.3 11.1 YES YES NO Comp 17 EX-14;Di-n-butylamine 20.8 16.9 9.3 7.7 8.0 YES YES NO Comp 18 EX-15;Di-iso-butylamine 19.7 16.5 8.8 6.1 6.9 YES YES NO Comp 19 EX-16;Dihexylamine 19.7 16.7 8.1 6.6 6.6 YES YES NO Comp20 EX-17;Diheptylamine 19.3 16.6 7.8 6.1 6.2 YES YES NO Comp.21 Ex-20;1-Hexadecylamine 18.9 16.7 6.9 5.5 5.8 YES YES NO Comp. 22 Ex-21;1-Hepatadecylamine 18.6 16.6 6.5 5.2 5.4 YES YES NO Comp. 23 Ex-22;1-octadecylamine 18.6 16.6 6.5 5.2 5.4 YES YES NO Comp 24

TABLE 3 Diesel Compatibility of PU Polymers with 100% p-iPO and MDI withvarious cap segments (MW = 2700 to 4000) Diesel compatibility CalculatedHansen Solubility (1 wt. %) Parameters (MPa^(1/2)) for End Polyol PolyolCap Segment and “End Cap” MW = 4000 MW = 2700 End Capping distance from“Diesel” (Ra) EX-23-30; EX-23-30; Example # Reagent δ_(T) δ_(D) δ_(P)δ_(H) Ra Comp25-27 Comp 25-27 EX-23 Methanol 28.4 19.1 16 13.6 17.5 YESYES EX-24 1-octanol 19.8 16.9 7.6 6.9 6.6 YES YES EX-25 Docosanol 17.116.2 4.3 3.4 4.4 YES YES EX-26 Dimethylamine 26.1 18.3 14.3 11.9 14.7YES YES EX-27 Dihexylamine 19.7 16.7 8.1 6.6 6.6 YES YES EX-28Didecylamine 18.3 16.4 6.3 5 5 YES YES Comp.25 1-butylamine 25.6 18.113.2 12.4 13.9 NO NO Comp. 26 1-octylamine 21.9 17.4 9.9 8.8 9.3 NO NOComp. 27 1-Pentadecylamine 19.3 16.8 7.4 5.9 6.2 NO NO Ex-291-Hexadecylamine 18.9 16.7 6.9 5.5 5.8 YES YES Ex-30 1-Octadecylamine18.6 16.6 6.5 5.2 5.4 YES YES

In accordance with the present invention, all mono alcohol, allsecondary amine, and primary amine with alkyl chains greater than C15capping agents were compatible

1. A method for preserving wood comprising: contacting wood with a woodpreservation composition comprising a) a polyurethane polymersynthesized from i) a polyol comprising >95% p-propylene oxide, ii) anisocyanate, and iii) a capping agent; b) an organic solvent; and c) atleast one wood preservative active selected from among halogenatedisothiazolone biocides, halogenated carbamate fungicides and azolefungicides; wherein the capping agent is selected from the groupconsisting of a mono alcohol, a secondary amine, a primary amine withalkyl chain greater than C15 and mixtures thereof; and further whereinthe molecular weight of the polyol is greater than or equal to
 2700. 2.The method of claim 1 in which the wood preservative active is4,5-dichloro-2-n-octyl-4-isothiazolin-3-one.
 3. The method of claim 1wherein the organic solvent comprises diesel.
 4. The method of claim 1wherein the polyol comprises 100% p-propylene oxide.
 5. The method ofclaim 1 wherein the isocyanate is a diisocyanate.
 6. A wood preservationcomposition comprising i) a polyol comprising >95% p-propylene oxide,ii) an isocyanate, and iii) a capping agent; b) an organic solvent; andc) at least one wood preservative active selected from among halogenatedisothiazolone biocides, halogenated carbamate fungicides and azolefungicides; wherein the capping agent is selected from the groupconsisting of a mono alcohol, a secondary amine, a primary amine withalkyl chain greater than C15 and mixtures thereof; and further whereinthe molecular weight of the polyol is greater than or equal to 2700.